Listen to Robert Emmerich introduce "The Big Apple," a hit song from 1937. Music written by Bob and performed by Tommy Dorsey's Clambake Seven with Bob on piano. Lyrics written by Buddy Bernier and sung by Edythe Wright. Audio provided by Dorothy Emmerich.

Wikipedia: Washington IrvingWashington Irving (April 3, 1783 – November 28, 1859) was an American author, essayist, biographer, historian, and diplomat of the early 19th century. He is best known for his short stories “Rip Van Winkle” (1819) and “The Legend of Sleepy Hollow” (1820), both of which appear in his book The Sketch Book of Geoffrey Crayon, Gent.
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In late 1809, while mourning the death of his seventeen-year-old fiancée Matilda Hoffman, Irving completed work on his first major book, A History of New-York from the Beginning of the World to the End of the Dutch Dynasty, by Diedrich Knickerbocker (1809), a satire on self-important local history and contemporary politics. Prior to its publication, Irving started a hoax akin to today’s viral marketing campaigns; he placed a series of missing person adverts in New York newspapers seeking information on Diedrich Knickerbocker, a crusty Dutch historian who had allegedly gone missing from his hotel in New York City. As part of the ruse, Irving placed a notice—allegedly from the hotel’s proprietor—informing readers that if Mr. Knickerbocker failed to return to the hotel to pay his bill, he would publish a manuscript Knickerbocker had left behind.

Unsuspecting readers followed the story of Knickerbocker and his manuscript with interest, and some New York city officials were concerned enough about the missing historian that they considered offering a reward for his safe return. Riding the wave of public interest he had created with his hoax, Irving—adopting the pseudonym of his Dutch historian—published A History of New York on December 6, 1809, to immediate critical and popular success. “It took with the public”, Irving remarked, “and gave me celebrity, as an original work was something remarkable and uncommon in America”. Today, the surname of Diedrich Knickerbocker, the fictional narrator of this and other Irving works, has become a nickname for Manhattan residents in general.

New York Knicks (NBA team offical website)What’s a Knickerbocker?
The Name...
The term “Knickerbockers” traces its origin to the Dutch settlers who came to the New World - and especially to what is now New York - in the 1600s. Specifically, it refers to the style of pants the settlers wore...pants that rolled up just below the knee, which became known as “Knickerbockers”, or “knickers”.

In 1809, legendary author Washington Irving solidified the knickerbocker name in New York lore when he wrote the satiric A History of New York from the Beginning of the World to the End of the Dutch Dynasty under the pseudonym Diedrich Knickerbocker. Later known as Knickerbocker’s History of New York, Irving’s book introduced the word “knickerbocker” to signify a New Yorker who could trace his or her ancestry to the original Dutch settlers.

With the publication of Irving’s book, the Dutch settler “Knickerbocker” character became synonymous with New York City. The city’s most popular symbol of the late 19th and early 20th centuries was “Father Knickerbocker”, complete with cotton wig, three-cornered hat, buckled shoes, and, of course, knickered pants.

At the same time, the term “Knickerbocker” became indelibly linked to anything and everything New York...from Jacob Ruppert’s Knickerbocker Beer to the 1938 Broadway musical Knickerbocker Holiday (which starred Walter Huston and featured the haunting “September Song") to famed society gossip columnists Cholly Knickerbocker (the nom de plume used by Maury Paul and Igor Cassini) and Suzy Knickerbocker (Aileen Mehle).

(Oxford English Dictionary)
knickerbocker, n.
Etymology: < the name of Diedrich Knickerbocker, the pretended author of Washington Irving's History of New York.
A descendant of the original Dutch settlers of the New Netherlands in America, hence, a New Yorker.
[1809 W. Irving (title) History of New York…By Diedrich Knickerbocker.]
1848 ‘D. Knickerbocker’ Hist. N.Y. (rev. ed.) p. xiv, When I find New-Yorkers of Dutch descent priding themselves upon being ‘genuine Knickerbockers’ [etc.].
1876 S. Osgood in D. J. Hill Bryant (1879) 158 We can all join,..whether native or foreign-born, Knickerbockers, or New-Englanders.